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What is React?

ReactJunior~1 min read
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React is a JavaScript library for building user interfaces (UI). It was developed by Facebook (Meta), and it is used to build interactive web applications, where the interface updates dynamically when data changes, without reloading the page.

Key features of React:

  1. Component-based approach An application in React is built from small, independent components - interface blocks (for example, a button, a form, a product card). Each component:
  • has its own state;
  • accepts input data (props);
  • and describes how the UI should look.
  1. Virtual DOM React does not change the real DOM directly. Instead, it creates a virtual copy of the DOM, compares it with the previous version (diffing), and updates only the changed parts of the interface - this makes React fast and efficient.
  2. One-way data flow Data in React flows from top to bottom - from a parent component to child components through props. This makes the application logic more predictable.
  3. JSX (JavaScript XML) This is a special syntax that allows you to write HTML-like code directly inside JavaScript:
javascript
function Hello() { return <h1>Hello, world!</h1>; }

JSX is then transformed into regular JS calls to React.createElement(). 5. React Hooks A modern way to work with state and the component lifecycle without classes:

javascript
import { useState } from "react"; function Counter() { const [count, setCount] = useState(0); return ( <button onClick={() => setCount(count + 1)}> Clicked {count} times </button> ); }

Advantages of React:

  • High performance (via Virtual DOM)
  • Reusable components
  • Large ecosystem (React Router, Redux, Next.js)
  • Active community and Meta support

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